Normally, we would consume server-sent events (SSE) in a web browser, but we can also consume them in our code on the server. Micronaut has a low-level HTTP client with a SseClient interface that we can use to get server-sent events. The interface has an eventStream method with different arguments that return a Publisher type of the Reactive Streams API. We can use the RxSseClient interface to get back RxJava2 Flowable return type instead of Publisher type. We can also use Micronaut's declarative HTTP client, which we define using the @Client annotation that supports server-sent events with the correct annotation attributes.

In our example, we first create a controller in Micronaut to send out server-sent events. We must create method that returns a Publisher type with Event objects. These Event objects can contains some attributes like id and name, but also the actual object we want to send:

Notice how easy it is in Micronaut to use server-sent events. Let's add a declarative HTTP client that can consume the server-sent events. We must set the processes attribute of the @Get annotation with the value text/event-stream. This way Micronaut can create an implementation of this interface with the correct code to consume server-sent events: